This Conservation Advice was approved by the Delegate of the Minister on 11 April 2014

Approved Conservation Advice for Pterostylis pratensis ( greenhood)

(s266B of the Environment Protection and Biodiversity Conservation Act 1999)

This Conservation Advice has been developed based on the best available information at the time this Conservation Advice was approved; this includes existing and draft plans, records or management prescriptions for this species.

Description

Pterostylis pratensis (liawenee greenhood), family Orchidaceae, is a deciduous, terrestrial orchid growing to 7 to 15 cm tall in flower, with a green hood-like structure dominating the flower. Pterostylis pratensis flowers from mid-November to mid-December. They have 2 to 12 densely crowded white flowers with dark green stripes. The flowers are 7 to 8.5 mm long and 4.5 mm wide. They have fleshy tubers which are replaced annually (TSU, 2008).

The darker green and white flowers and larger leaves can distinguish Pterostylis pratensis, which grows in montane and subalpine regions on the Tasmanian Central Plateau from another similar greenhood, Pterostylis ziegeleri, a greenhood of lowland areas. The dark green apex on the appendage of the labellum of Pterostylis pratensis is also broader and blunter than that of Pterostylis ziegeleri. A similar greenhood found below Table Mountain needs further investigation (TSU, 2008).

Conservation Status

Pterostylis pratensis (liawenee greenhood) is listed as vulnerable under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) under the name Pterostylis pratensis (liawenee greenhood). In 2001 the species was found eligible for listing as “the number of mature individuals recorded, 600, was low” (TSSC, 2001).

This species is also listed as vulnerable in under the Tasmanian Threatened Species Protection Act 1995 (TSP Act). Note, however, that in 2009 the state government Threatened Species Section undertook an assessment of all Tasmanian orchid species, and made recommendations on their conservation status under the TSP Act (TSS, 2009). This review indicated that several species, including Pterostylis pratensis, probably warrant delisting. The finding for this species was due to a further population being found in 2009. The Tasmanian Scientific Advisory Committee to the TSP Act is currently reviewing all species listed on the TSP Act. This will consider the recommendations of TSS (2009). The listing of this species will subsequently be re-considered under the EPBC Act.

Distribution and Habitat

Pterostylis pratensis is endemic to Tasmania and occurs at an altitude of 850 to 1100 m. It grows in subalpine Poa labillardierei tussock grassland which is very exposed, low and open, with patches of often stunted Olearia algida and Hakea microcarpa scrub on red–brown loamy to clay soils derived from basalt. Pterostylis pratensis grows in montane and subalpine regions on the Central Plateau (TSU, 2008). The habitat requirements, and disturbance regimes required to maintain suitable habitat, are not well known.

There are 11 known populations of Pterostylis pratensis (TSS, 2013). Estimating the size of populations of terrestrial orchids is often difficult unless conditions are favourable for flowering. In 2008 the largest population, on Liawenee Moor, had a maximum of 500 plants, and the total number of individuals was estimated to be at least 600. The species was estimated to extend over an area of approximately 400 square kilometres, occupying an area of 20 or more hectares in total (TSU, 2008). An ecological survey report has since identified a large population covering hundreds of hectares and estimated to be in excess of 10 000 plants (SEMF Pty Ltd, 2009).

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Pterostylis pratensis is not well represented in conservation reserves, with all but two known populations occurring on private land (TSS, 2013). The Lake Augusta/Lake Botsford sites are in the Central Plateau Conservation Area, which is included in the Tasmanian Wilderness World Heritage Area (TSU, 2008).

The species occurs in the Tasmanian Central Highlands IBRA bioregion, and the South and North West Tasmanian Natural Resource Management Regions.

The distribution of this species is not known to overlap with any EPBC Act-listed threatened ecological community.

Threats

There is little information on the level of threat to Pterostylis pratensis. The Liawenee Moor population is outside the World Heritage Area, and has been subject to grazing and frequent burning. These factors have probably maintained an open grassy habitat for the species. The St Patricks Plains colonies are on private land used for grazing. They are confined to a rocky basalt exposure which has not been ploughed or fertilised, unlike adjacent similar habitat where the species could not be found. Clearing, cultivation and fertilisers are the main threats to any other colonies that may occur on private land in the district. Colonies in the World Heritage Area should be safe in the long-term, provided Poa tussocks are occasionally burnt. Checks in apparently suitable habitat along the Lake Highway have shown Pterostylis pratensis to be very patchy in distribution, suggesting that stochastic risks are a relevant consideration (TSU, 2008).

Research Priorities

Research priorities that would inform future regional and local priority actions include:

• assessing and identifying physical and biological habitat requirements • determining appropriate grazing regimes for Pterostylis pratensis • determining appropriate fire regimes required to keep the habitat of Pterostylis pratensis open

Priority Actions

The following priority recovery and threat abatement actions can be done to support the recovery of Pterostylis pratensis:

• Monitor known populations for threats and declines. • Survey to determine whether there are any more populations in existence, from mid- November to mid-December when the plants are in flower. • Verify older records. • Establish a mechanism to ensure management intervention when required. • Undertake appropriate seed and mycorrhizal fungi collection and storage, and conduct mycorrhizal fungi association trials. • Coordinate implementation, including manage and analyse data, review the progress of recovery and effectiveness of management actions, and adapting actions if necessary. Habitat Disturbance and Modification • Pursue management options with landowners/managers to protect populations of Pterostylis pratensis against possible changes in land use that would be detrimental, particularly regarding ploughing and fertilising of pastures, and grazing levels. • Promote conservation options for private land e.g. private nature reserve, management agreement, covenants.

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Conservation Information • Communicate with and engage the community and stakeholders regarding conservation of Pterostylis pratensis. • Communicate management information to landholders e.g. ensuring Poa tussock grasslands in the vicinity of populations remain open through occasional burning or grazing; not overgrazing from November to January to avoid damaging colonies and to allow plants to set seed; not ploughing or fertilising in the vicinity of Pterostylis pratensis populations.

This list does not necessarily encompass all actions that may be of benefit to Pterostylis pratensis, but highlights those that are considered to be of highest priority at the time of preparing the Approved Conservation Advice.

Existing Plans/Management Prescriptions that are Relevant to the Species

• The world heritage area is managed to protect and preserve its wilderness values (TPWS, 1999 and 2002). • The draft threatened Tasmanian orchids flora recovery plan (TSS, 2013) was released for public comment on 23 November 2013. This plan outlines recovery actions for all threatened orchid species within Tasmania, including Pterostylis pratensis.

These plans/prescriptions were current at the time of publishing; please refer to the relevant agency’s website for any updated versions.

References

SEMF Pty Ltd (2009). Proposed Cattle Hill Wind Farm ecological survey for National Power Pty Ltd. Hobart.

Tasmanian Parks and Wildlife Service (TPWS) (1999 and 2002) Tasmanian Wilderness World Heritage Area management plan 1999 and 2002. Department of Primary Industries, Water and Environment, Hobart.

Threatened Species Section (TSS) (2009). Summary of surveys and actions arising from the threatened orchid and Euphrasia project 2006–2009. Department of Primary Industries Parks Water and the Environment, Hobart.

Threatened Species Section (TSS) (2013). Draft threatened Tasmanian orchids flora recovery plan. Department of Primary Industries, Parks, Water and Environment, Hobart.

Threatened Species Scientific Committee (TSSC) (2001). Commonwealth Listing advice on Pterostylis pratensis. Available on the Internet at: http://www.environment.gov.au/biodiversity/threatened/species/p-pratensis.html

Threatened Species Unit (TSU) (2008). Listing statement Pterostylis pratensis. Department of Primary Industries and Water, Hobart.

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